Clustering Nominal data with Equivalent Categories

The problem considered in the present paper is how to cluster data of nominal measurement level, where the categories of the variables are equivalent (the variables are replications of each other). One suitable technique to obtain such a clustering is latent class analysis (LCA) with equality restrictions on the conditional probabilities. As an alternative, a less well known technique is introduced: GROUPALS. This is an algorithm for the simultaneous scaling (by multiple correspondence analysis) and clustering of categorical variables. Equality restrictions on the category quantifications were incorporated in the algorithm, to account for equivalent categories. In two simulation studies, the clustering performance was assessed by measuring the recovery of true cluster membership of the individuals. The effect of several systematically varied data features was studied. Restricted LCA obtained good to excellent cluster recovery results. Restricted GROUPALS approximated this optimal performance reasonably well, except when underlying classes were very different in size.

     

Surgical variables affecting speech in treated patients with oral and oropharyngeal cancer

A well-characterized collagen-glycosaminoglycan matrix (CGM) that has been shown to function as a dermal analog was seeded with freshly disaggregated autologous keratinocytes and applied to full-thickness wounds in a porcine model. CGM were impregnated with 50,000 keratinocytes per cm2, a seeding density that produces a confluent epidermis within 19 d post-grafting and affords a 60-fold surface expansion of the donor epidermis. In this study, the temporal sequence of events in epidermal and neodermal formation was analyzed histopathologically and immunohistochemically from 4 to 35 d post-grafting. The epidermis was observed to form from clonal growth of individual keratinocytes into epithelial cords and islands that gradually enlarged, coalesced, differentiated to form large horn cysts, and finally reorganized at the graft surface to form a fully differentiated, normally oriented epidermis with rete ridges. Simultaneously, a neodermis formed from migration of endothelial cells, fibroblasts, and macrophages into the CGM from the underlying wound bed, resulting in formation of blood vessels, the production of abundant extracellular matrix, and the degradation of the CGM fibers, respectively. Gradually, the stromal cellularity of the CGM decreased and collagen deposition and remodeling increased to form a neodermal connective tissue matrix beneath the newly formed epidermis. Complete dissolution of the CGM occurred, partly as a result of degradation by an ongoing foreign-body giant cell reaction that peaked at 8-12 d post-grafting, but neither acute inflammation nor evidence of immune stimulation were observed. Within 1 mo, many structural components of normal skin were reconstituted.     

Psychology and the State Associations.

Comments upon Robert Perloff's comment (1964) on state associations. The author mentions some things that Perloff might discover if he approached the problem as a psychologist. It is noted that the status and support of any science or profession depends upon public understanding and appreciation. In simple self-interest, any psychologist who takes the trouble to be informed in these matters, and who wants to support himself rather than live on the efforts of his colleagues, will join his efforts with theirs to insure professional standards and status for those who serve the public in the name of psychology. This means support and utilization of state associations, for there is no other organ so well adapted to deal with professional problems and the public's interest. Also, aside from the important questions of standards and competence, state associations are ideally situated to deal constructively with the divisive forces in American psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in strategy use on division problems: Mental versus written computation.

Individual differences in strategy use (choice and accuracy) were analyzed. A sample of 362 Grade 6 students solved complex division problems under 2 different conditions. In the choice condition students were allowed to use either a mental or a written strategy. In the subsequent no-choice condition, they were required to use a written strategy. Latent class analysis showed that there were 3 subgroups of students with respect to pattern of strategy choices: primarily using a written strategy (more girls than boys); primarily using a mental strategy (more boys than girls); and using a written strategy on more difficult items but a mental strategy on the easier ones (almost no weak mathematical achievers). Strategy accuracies were analyzed with explanatory item response theory modeling. A between-subjects comparison in the choice condition showed that written strategies were usually more accurate than mental strategies, especially for the weak achievers. A within-subject comparison showed that the performance of students who used mental calculation on a particular item in the choice condition improved if they were required to use a written strategy in the no-choice condition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Strategies to gain body condition score in pasture-based dairy cows during late lactation and the far-off nonlactating period and their interaction with close-up dry matter intake

In pasture-based systems, cows are generally thinner at the end of lactation than cows fed total mixed rations and, as a result, over-feeding of metabolizable energy (ME) during the far-off nonlactating period is a standard management policy to achieve optimum calving body condition score (BCS). An alternative would be to manage cows to gain BCS through late lactation, such that cows ended lactation close to optimum calving BCS and maintenance of BCS through to calving. We sought to quantify the effect of moderate or excessive ME intakes during the far-off nonlactating period in cows that had been managed to gain or maintain BCS through late lactation and whether the far-off management strategy interacted with close-up level of feeding. Effects on milk production and circulating indicators of energy balance and metabolic health in early lactation were evaluated. A herd of 150 cows was randomly assigned to 1 of 2 feeding levels in late lactation to achieve a low and high BCS at the time of dry-off (approximately 4.25 and 5.0 on a 10-point scale). Following dry-off, both herds were managed to achieve a BCS of 5.0 one month before calving; this involved controlled feeding (i.e., maintenance) and over-feeding of ME during the far-off dry period. Within each far-off feeding-level treatment, cows were offered 65, 90, or 120% of their pre-calving ME requirements for 3 wk pre-calving in a 2 × 3 factorial arrangement (i.e., 25 cows/treatment). Body weight and BCS were measured weekly before and after calving, and milk production was measured weekly until wk 7 postcalving. Blood samples were collected weekly for 4 wk pre-calving and 5 wk postcalving, and on d 0, 1, 2, 3, and 4 relative to calving, and analyzed for indicators of energy balance (e.g., blood fatty acids, β-hydroxybutyrate), calcium status, and inflammatory state. No interaction was observed between far-off and close-up feeding levels. Over-feeding of ME to low BCS cows during the far-off nonlactating period reduced blood fatty acid and β-hydroxybutyrate concentrations in early lactation, and increased blood albumin to globulin ratio compared with cows that were dried off close to recommended calving BCS and control-fed during the far-off dry period. Cows consuming 65% of their ME requirements during the close-up period had lower fatty acids and β-hydroxybutyrate in early lactation, but produced less milk, particularly during the first 21 d of lactation, had more than 3-fold greater concentration of haptoglobin immediately postcalving, and had a lower blood cholesterol concentration and albumin to globulin ratio, when compared with cows offered 90 or 120% of their ME requirements. Collectively, these measurements indicate that a severe restriction (<70% of ME requirements) during the close-up nonlactating period increases the risk of disease in early lactation and reduces milk production. In summary, far-off over-feeding of ME to cows that needed to gain BCS did not influence peripartum metabolic health in grazing dairy cows, but restricting cows below 70% ME requirements during the close-up transition period resulted in a blood profile indicative of greater inflammation.     

American Board for Psychological Services: 1955 Annual Report.

This article is a brief annual report from the American Board for Psychological Services (ABPS). It is noted that since the APA convention in 1954, the ABPS has had 3 meetings, all of which were attended by the entire Board. The work of the Board in 1955 has consisted of: (1) Exploration of relationships within the profession of psychology, (2) Exploration of relationships between psychology and other professions, (3) Development of procedures of evaluation for agencies that apply, and (4) The interpreting of the purpose of the Board to the profession of psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Angle-resolved photoelectron spectroscopy of C60

The V3 loop of the gp120 of human immunodeficiency virus type 1 (HIV-1) is assumed to be involved in HIV-1-mediated membrane fusion. V3-derived peptides have been shown either to enhance or to prevent HIV-1 infection. Multibranched peptide constructs (MBPCs) derived from the V3 North American/European consensus sequence were designed to sort out these conflicting findings. At 5 microM, MBPC1 (8-branched GPGRAF) totally, and MBPC2 ([RKSIHIGPGRAFYT]4) partially, inhibited HIV-1LAI infection, whereas the GPGRAF monomer had only a limited effect. A peptide of the entire V3 consensus loop and a control MBPC had no detectable activity. The 5 microM MBPC1 HIV-1-inhibiting concentration was not cytotoxic, nor did it alter T lymphocyte allogeneic, antigen-, or mitogen-induced reactivities, and it was about 5- to 50-fold lower (MBPC2 and MBPC1, respectively) than that resulting in 50% cell death. Analysis of MBPC immunoreactivity showed that MBPC2, but not MBPC1, strongly reacted with human HIV-1 positive sera. Only MBPC2 elicited significant antibody responses in rabbits. The V3-derived MBPCs bound to CD4+ cells, as determined by immunofluorescence analysis. The binding was inhibited either by soluble CD4 or by CD4 monoclonal antibody (mAb) MT151, which recognizes the CDR3 region of the D1 domain of CD4, but not by other CD4 mAbs Leu3a, OKT4A, Q4021, 13B8-2, 5A8, RFT4, nor by the CD26 mAb BA5. Therefore, it appears likely that MBPCs inhibit HIV-1 infection by interacting with the CDR3 region of CD4 or with a region in its vicinity.